I don’t get the desire for consistently bad. Think about with fruit—-yes it’s disappointing to bite into a cantaloupe from the same supermarket that last week you had a sublime one from and find it tasteless. But if you told me I could fix the inconsistency by always getting ones that tasted bad, I’d say you were nuts.
I think instead it has to do with the percentage of their clients that add sweeteners, perhaps the bitterness is better somehow as the base of a sugary drink.